title: Primary hemostasis in neonates with thrombocytopenia.
abstract: OBJECTIVE
  To evaluate the relationship between platelet counts and the platelet function analyzer-100 closure times (CTs) in neonates with thrombocytopenia, and to determine what other factors significantly affect CTs.
  
  
  METHODS
  In a single institution prospective cross-sectional study, blood samples from neonates with platelet counts <150 × 10(9)/L were tested on the platelet function analyzer-100 with CT-collagen/epinephrine (CT-Epi) and CT-collagen/adenosine diphosphate (CT-ADP) cartridges.
  
  
  RESULTS
  The mean platelet count was 95 ± 28 × 10(9)/L for 48 infants with a mean gestational age 30.9 ± 5.3 weeks and median postnatal age of 5 (3-18) days. No association was evident between CT-Epi and platelet count. However, the CT-ADP was prolonged in many (but not all) infants with platelet counts <90 × 10(9)/L. Among infants <32 weeks gestational age, we found a moderate negative correlation between CT-ADP and platelet count (r = -0.54, P = .0045). The negative correlation was strongest in infants <32 weeks and <10 days old (r = -0.8, P = .0017). Other variables examined (hematocrit, infection, Score of Neonatal Acute Physiology II) did not have a significant effect on CT-ADP in a linear regression model.
  
  
  CONCLUSIONS
  Platelet counts <90 × 10(9)/L are associated with prolonged CT-ADP times in some but not all infants. Gestational and postnatal age-related differences in platelet function account for some of this variability. The predictive value of CT-ADP on neonatal bleeding risk remains to be studied.
authors.affiliation: Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA; Division of Neonatology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Emoke
authors.initials: E
authors.lastname: Deschmann
authors.affiliation: Division of Newborn Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors.forename: Martha
authors.initials: M
authors.lastname: Sola-Visner
authors.affiliation: Division of Neonatology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL; Department of Pediatrics, Levine Children's Hospital/Jeff Gordon Children's Hospital, Carolinas Healthcare System, Concord, NC.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Saxonhouse
mesh_terms: D001792:Blood Platelets / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006400:Hematocrit; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010976:Platelet Count; D010979:Platelet Function Tests; D011446:Prospective Studies; D013921:Thrombocytopenia / Q000097:blood*
keywords: CT; CT-ADP; CT-Epi; Closure time; Closure time-collagen/adenosine diphosphate; Closure time-collagen/epinephrine; NICU; Neonatal intensive care unit; PFA-100; Platelet function analyzer-100; SNAP II; Score of Neonatal Acute Physiology, Version II